The two-spotted spider mite is the most common 'warm season' mite. The females over-winter in the soil or on the plants, either in the yard, garden or in potted plants stored for the winter and become active early Spring.
Perfect Spider Mite Weather
Dry conditions greatly favor spider mites, plus plants stressed by drought can produce changes in their chemistry that make them more nutritious to spider mites. Therefore they can develop rapidly during this time, in as little as a week after hatching the females produces a dozen eggs daily for a couple of weeks. The fast development rate and high egg production can lead to rapid increases in mite populations
Early Detection
Early detection of spider mites, before damage is noticed, is important. The tiny spider mites can be detected by holding either a piece of white paper or cardboard under a leaf, then thump the front side of the leaf. If mites are present, they will be dislodged and can be seen walking slowly on the paper.
Quarantine and Inspection.
Mites as well as other insects, virus and fungus are often introduced into your environment on infested plants or their soil. Carefully inspect, preferably with a magnifying lens, any plant or cutting being introduced into your environment. Do the above white paper test for mites and inspect the total plant for other insects and problems. If mites or insects are detected and the plant was purchased it should be immediately returned to the vendor.
If you are bringing in plants without soil or cuttings, swishing it a 10% Clorox solution to which Ivory dish washing liquid has been added will be of benefit as would a dip in a medicide or insecticide solution with good miticide activity such as (Talstar). However if upon inspection mites, are detected on plants you can’t take back, consider toss them before you get attached. If you won’t toss a full mite treatment should be given. Be sure to quarantine all new plants for a minimum of 4 weeks, to insure they are clean.
Spider Mite Treatment
To eliminate Spider Mites, trim, bag and removed heavily infested leaves, clean up all plant debris … discard severely infested plants. Choose one of the following pesticides/miticides and follow the instructions. Be sure to continue your spraying program until all eggs are hatched and the resulting mites are killed. Some of the miticides listed kill both adults and eggs but are very expensive and may not be available to non-professionals.
NOTE: Spider Mites hatch in 3-20 days after they are laid, depending upon the weather. The hotter and dryer it is the faster they hatch. I believe mites have continued to give me a problem because I didn’t spray long enough to kill the last hatching eggs. Also washing them off with the water hose caused them to drop into the soil in and around the pot, so they missed the pesticide.
The following information on pesticides is from http://www.ext.colostate.edu/PUBS/INSECT/05507.html
The list was last reviewed Jan 2004, therefore Forbid and more recent products are not included
Table 1: Pesticides useful to control spider mites in yards and gardens. (Not to be used inside the house.)
Active Ingredient Trade Name(s)
Comments second line
Acephate, Orthene & certain Isotox formulations
Insecticide with some effectiveness against spider mites. Systemic.
Personal experience - JudyCooksey: damages the leaves of some Brugs & tender plants.
Abamectin, Avid (Recommended by Monika)
For commercial use only on ornamental plants. Primarily effective against two-spotted spider mite; less effective against mites on conifers. Limited systemic movement.
Bifenthrin, Talstar & others
Insecticide with good miticide activity.
Dimethoate, Cygon
Insecticide with fair miticidal activity. Few food crop registrations. Systemic.
Dicofol, Kelthane
Selective miticide labeled for some food crops in addition to ornamental plants. Some reduced activity at higher temperatures.
Hexythiazox, Hexygon
For commercial use only on ornamental plants. Selective miticide that affects developing stages and eggs only. One application per season label restriction.
Horticultural oils, Sunspray & others
Used at the "summer oil" rate (2 percent), oils are perhaps the most effective miticide available for home use.
Insecticidal soap, several
Marginally effective against two-spotted spider mite and where webbing prevents penetration. Broadly labeled.
Sulfur, various
Generally sold in dust formulation for control of various fungal diseases and some mites on some ornamental and vegetable crops.
(1W.S. Cranshaw, Colorado State University Cooperative Extension entomologist and professor, and D.C. Sclar, research assistant; bioagricultural sciences and pest management. Reviewed 1/04.)
Wintering-Over Brugmansias
Spider Mites in the house can be particularly frustrating because the only safe chemical controls are soaps and horticultural oils, pesticide treatments should be done outside not in the house.
In the home environment spider mites can stay active all winter since the warm season continues. Those stored for the winter where temperatures are cooler, but above freezing should not reach damaging populations.
If spider mites are identified, it is recommended that all susceptible plants, not just your brugmansia be treated at the same time. Trim, bag and remove heavily infested leaves and discard severely infested plants, hose small plants in the sink or shower. Wipe leaves of larger plants with a soft, damp cloth. When the plants are dry use soaps, horticultural oils not necessary to take them outside but if you opt for pesticide do this outside only. Reapply these treatments every 5 days as long as populations persist.
Doing it the organic way…. http://www.ghorganics.com/page9.html#Mites
Additional Reading
http://www.mobot.org/gardeninghelp/plantfinder/IPM.asp?code=115&group=48&level=s
http://www.negreenhouseupdate.info/greenhouse_update/?p=2453
This is a write up I prepared for myself and thought I would share it in hopes that it would give a jumpstart to the “newbies”.
I encourage all experienced brug growers to post comments, tell me immediately if I’ve made an error or provide us with personal experience with a specific pesticide.
I compiled this information from several sources: Brugmansia Forum threads, my online research and conversations with my County Ag Agent. I have included the information on pesticides and miticides because so many questions have been asked about them.
